virtio_net: avoid data-races on dev->stats fields

[ Upstream commit d12a26b ]

Use DEV_STATS_INC() and DEV_STATS_READ() which provide
atomicity on paths that can be used concurrently.

Reported-by: syzbot <[email protected]>
Signed-off-by: Eric Dumazet <[email protected]>
Reviewed-by: Xuan Zhuo <[email protected]>
Cc: "Michael S. Tsirkin" <[email protected]>
Cc: Jason Wang <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
Stable-dep-of: 2311e06 ("virtio_net: fix missing dma unmap for resize")
Signed-off-by: Sasha Levin <[email protected]>

Author: Eric Dumazet

drivers/net/virtio_net.c

@@ -1258,7 +1258,7 @@ static struct sk_buff *receive_small(struct net_device *dev,
 	if (unlikely(len > GOOD_PACKET_LEN)) {
 		pr_debug("%s: rx error: len %u exceeds max size %d\n",
 			 dev->name, len, GOOD_PACKET_LEN);
-		dev->stats.rx_length_errors++;
+		DEV_STATS_INC(dev, rx_length_errors);
 		goto err;
 	}
 
@@ -1323,7 +1323,7 @@ static void mergeable_buf_free(struct receive_queue *rq, int num_buf,
 		if (unlikely(!buf)) {
 			pr_debug("%s: rx error: %d buffers missing\n",
 				 dev->name, num_buf);
-			dev->stats.rx_length_errors++;
+			DEV_STATS_INC(dev, rx_length_errors);
 			break;
 		}
 		u64_stats_add(&stats->bytes, len);
@@ -1432,7 +1432,7 @@ static int virtnet_build_xdp_buff_mrg(struct net_device *dev,
 			pr_debug("%s: rx error: %d buffers out of %d missing\n",
 				 dev->name, *num_buf,
 				 virtio16_to_cpu(vi->vdev, hdr->num_buffers));
-			dev->stats.rx_length_errors++;
+			DEV_STATS_INC(dev, rx_length_errors);
 			goto err;
 		}
 
@@ -1451,7 +1451,7 @@ static int virtnet_build_xdp_buff_mrg(struct net_device *dev,
 			put_page(page);
 			pr_debug("%s: rx error: len %u exceeds truesize %lu\n",
 				 dev->name, len, (unsigned long)(truesize - room));
-			dev->stats.rx_length_errors++;
+			DEV_STATS_INC(dev, rx_length_errors);
 			goto err;
 		}
 
@@ -1630,7 +1630,7 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
 	if (unlikely(len > truesize - room)) {
 		pr_debug("%s: rx error: len %u exceeds truesize %lu\n",
 			 dev->name, len, (unsigned long)(truesize - room));
-		dev->stats.rx_length_errors++;
+		DEV_STATS_INC(dev, rx_length_errors);
 		goto err_skb;
 	}
 
@@ -1662,7 +1662,7 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
 				 dev->name, num_buf,
 				 virtio16_to_cpu(vi->vdev,
 						 hdr->num_buffers));
-			dev->stats.rx_length_errors++;
+			DEV_STATS_INC(dev, rx_length_errors);
 			goto err_buf;
 		}
 
@@ -1676,7 +1676,7 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
 		if (unlikely(len > truesize - room)) {
 			pr_debug("%s: rx error: len %u exceeds truesize %lu\n",
 				 dev->name, len, (unsigned long)(truesize - room));
-			dev->stats.rx_length_errors++;
+			DEV_STATS_INC(dev, rx_length_errors);
 			goto err_skb;
 		}
 
@@ -1763,7 +1763,7 @@ static void receive_buf(struct virtnet_info *vi, struct receive_queue *rq,
 
 	if (unlikely(len < vi->hdr_len + ETH_HLEN)) {
 		pr_debug("%s: short packet %i\n", dev->name, len);
-		dev->stats.rx_length_errors++;
+		DEV_STATS_INC(dev, rx_length_errors);
 		virtnet_rq_free_unused_buf(rq->vq, buf);
 		return;
 	}
@@ -1803,7 +1803,7 @@ static void receive_buf(struct virtnet_info *vi, struct receive_queue *rq,
 	return;
 
 frame_err:
-	dev->stats.rx_frame_errors++;
+	DEV_STATS_INC(dev, rx_frame_errors);
 	dev_kfree_skb(skb);
 }
 
@@ -2352,12 +2352,12 @@ static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev)
 
 	/* This should not happen! */
 	if (unlikely(err)) {
-		dev->stats.tx_fifo_errors++;
+		DEV_STATS_INC(dev, tx_fifo_errors);
 		if (net_ratelimit())
 			dev_warn(&dev->dev,
 				 "Unexpected TXQ (%d) queue failure: %d\n",
 				 qnum, err);
-		dev->stats.tx_dropped++;
+		DEV_STATS_INC(dev, tx_dropped);
 		dev_kfree_skb_any(skb);
 		return NETDEV_TX_OK;
 	}
@@ -2576,10 +2576,10 @@ static void virtnet_stats(struct net_device *dev,
 		tot->tx_errors  += terrors;
 	}
 
-	tot->tx_dropped = dev->stats.tx_dropped;
-	tot->tx_fifo_errors = dev->stats.tx_fifo_errors;
-	tot->rx_length_errors = dev->stats.rx_length_errors;
-	tot->rx_frame_errors = dev->stats.rx_frame_errors;
+	tot->tx_dropped = DEV_STATS_READ(dev, tx_dropped);
+	tot->tx_fifo_errors = DEV_STATS_READ(dev, tx_fifo_errors);
+	tot->rx_length_errors = DEV_STATS_READ(dev, rx_length_errors);
+	tot->rx_frame_errors = DEV_STATS_READ(dev, rx_frame_errors);
 }
 
 static void virtnet_ack_link_announce(struct virtnet_info *vi)